Transformer tap changer mechanism



Jan. 21, 1958 w. J. GUTHBERTSON 2,320,953

TRANSFORMER TAP CHANGER MECHANISM Filed Aug. 24, 1954 2 Sheets-Sheet 1 Jan. 21, 1958 w. J. CUTHBERTSON 2,820,953

TRANSFORMER TAP CHANGER MECHANISM 2 Sheets-Sheet 2 Filed Aug. 24, 1954 ii E5??? United States Patent 2,820,953 TRANSFORMER TAP CHANGER MECHANISM William J. Cuthbertson, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application August 24, 1954, Serial No. 451,798 4 Claims. (Cl. 336-45) The present invention relates to electrical transformers and more particularly, to a tap changer operating mechanism therefor.

In the operation of transformers, it is often desirable or necessary to adjust the voltage ratio between the primary and secondary windings from time to time. For

this purpose, one or both of the transformer windings may be provided with a plurality of tap leads connected between different points along the winding and a switch or tap changer device, so that by actuation of the switch device a selected number of turns of the winding may be excluded from or included in the winding circuit. By this means, the effective number of turns in the winding, and thereby the voltage ratio of the transformer, may be varied as desired. tap-changer switch device has generally been located within the transformer casing adjacent the windings, and the mechanism for manually operating the switch has been placed heretoforein locations which are not easily accessible and which are cumbersome in construction.

These disadvantages are especially marked in the tap changer arrangements heretofore used in power transformers, which are generally of large size and extend to a considerable height above the operator. In such transformers, the tap changer drives have normally been located at the upper portions thereof, so that an operator required the use of a ladder to reach the tap changer drive in order to operate it. Further, in such transformers, various electrical parts such as the terminals, terminal boards, bushings and the like are normally located at the top or upper portions of the transformer. Consequently, in addition to the inconvenience of operating tap changer drives at the top of the transformer, there was substantial risk of injury to the operator due to possible contact with the electrically charged parts of the transformer. Besides, in the known arrangements there is considerable interference produced by the tap changer drive mechanism with such electrical parts when it is mounted in the upper portions of the transformer.

It is, therefore, an object of the present invention to provide a tap changer arrangement which is convenient for operation by an operator at the floor or base level of the transformer.

It is another object of the present invention to provide 7 a transformer tap changer drive which efficiently utilizes available space within the transformer apparatus without interference with electrical connections and mechanical parts involved in normal transformer operation.

It is a further object of the invention to provide a tap changer drive of the above type which atfords minimum risk of injury to the operator.

It is still another object of the invention to provide a transformer tap changer drive which is simple in construction and reliable in operation, which facilitates inspection and maintenance thereof, and which provides for accurate indication of the position of the tap changer switch.

With the above objects in view, the present invention involves a novel tap changer arrangement in a trans- In known types of transformers, the- 3 ice former apparatus having a winding enclosed within a housing arranged on a supporting surface with the housing extending upwardly from the supporting surface substantially above the height of an operator on the supporting surface, the arrangement in accordance with the invention comprising switch means arranged within the housing adjacent the winding and being connected to the winding, the switch means being operable to vary the effective number of turns of the winding. A manually operable drive means is mounted on the exterior of the housing at the lower portion thereof so as to be within the reach of an operator on the supporting surface on which the housing rests, and connecting means are arranged within the housing extending downwardly from the switch means and connecting the manually operable drive means to the switch means. In this way, the switch means may be conveniently operated to vary the voltage ratio of the transformer by an operator standing on the floor level of the transformer merely by manipulation of the manually operable drive means which is within easy reach from the floor.

In a preferred form of the invention, the drive mechanism is associated with a cover which may be removed from the transformer housing for maintenance and inspection purposes, and, further, the drive mechanism is equipped with indicating means for indicating the position of the contact member in the tap changer switch.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, however, together with further objects and advantages thereof, may best be under- Fig. l is a perspective view partly in section of a transformer apparatus embodying the present invention;

Fig. 2 is a detailed view, partly in section, of a tap changer drive mechanism constructed in accordance with the invention;

Fig. 3 is a cross-sectional view of the tap changer switch taken along the line 3-3 of Fig. 2; and

Fig. 4 is a detailed view of an indicating deviceused in accordance with the invention, this view being taken along the line 44 of Fig. 2.

Referring now to the drawings, and particularly to Fig. 1, there is shown a transformer apparatus which includes a housing or outer casing 1 resting with its base plate 2 on a floor or other supporting surface 3. Arranged within the transformer housing 1 is a winding or coil 4 having a surrounding cylindrical covering. The transformer includes a core 5 passing through the winding 4 and projecting laterally thereof at the top and bottom of the housing 1. Clamps 6a, b, c, d serve to hold the winding and core in position within the transformer housing 1.

A cover 7 is arranged closing the top of the transformer housing, the cover having insulating bushings 8, 8a and the like mounted thereon to receive the terminals of the windings of the transformer, such as exemplified by lead cable 9. Extending vertically within the transformer housing 1 is a tube 10 made preferably of insulating material and mounted at its bottom on the upper flange 39 of clamp 6b and secured at its top to an upper clamp or other suitable supporting member, as shown in Fig. 1. Arranged within tube 10 are tap changer switches 11 and 12. While two tap changer switches are illustrated in the drawing to show an arrangement suitable for a transformer having a plurality of windings, only one of which is shown in Fig. 1, it should be understood that a single tap changer may be mounted adjacent any particular winding forchanging the taps connected thereto. Tube 10 is formed with apertures 10a and 10b throughwhich the tap lead cables 13 are adapted to pass.

The form of transformer apparatus shown in Fig. 1, a type which is commonly used at present, is representative of large forced-oil transformers in which insulating oil fillsthe housing 1 and'is circulated under pressure for cooling purposes, by meansnot shown in the draw-- ing, through the' winding, and insuch transformer a The construction and arrangement of the partsv of the present tap changer drive is more clearly illustrated in detail in Fig. 2. Arranged within tube there is provided a downwardly extending connecting structure which is secured at its upper end to a rotatable contact mechanism 16 of the tap changer switch 11. The construc-' tion of the rotatable contact 16 is more clearly shown in Fig. 3, and the switch 11 is generally of the construction disclosed in U. S. Patent 2,255,501 in the name of L. F. Blume, dated June 30, 1937, and assigned to the same assignee as the present application. It will be understood that while the tap changer drive mechanism of the present invention is particularly suitable for use with a tap changer switch of this type, it is not limited to use with such switches.

The downwardly extending connecting structure which is secured to switch 11, in the particular form illustrated in Fig. 2, includes a rotatable shaft 17 which is connected by upper sleeve member 18a to a coupling 18 formed preferably of insulating material. The lower end of coupling 18 passes through the upper flange 39 of clamp 6b and is removably secured at its lower end by lower sleeve member 18b to a vernier joint 19. The latter joint, which connects coupling 18 to a bevel gear 20, allows the setting of the bevel gear 20 at a desired rotational position relative to the coupling 18. This can be accomplished, for example, by the provisionof a plurality of circumferentially spaced apertures in one of the plates of the vernier joint 19 into which the bolts 21 may be selectively inserted.

It will be noted that coupling structure 18, 18a, and

18b is attached at its upper and lower ends by pin and slot arrangements 24 and 25 which provide for selfalignment of the coupling, as. well as facilitate. its. assembly and disassembly within the transformer :housing. Support for the downwardly extending connecting structure is afforded bythrust bearing 43 which rests ,onthe horizontalrflange of anglemember 42, vernier joint 19' being rotatably carriedby, bearing 43 and the shaft of bevel; gear-20 beingrjournaled therein. Angle member 42.,is detachably securedto bracketv 41, which in turn.

is mounted onweb portion .40.of clamp 6b.

Bevel gear ;22, is ,journaledninthe vertical flange of.

angle member 42 for rotation about an axis at right angles to the axis of bevel Fgear 20 and is arranged to drive the latter'gear. Bevel gear22 is driven by a horizontal connecting structurewhich extends transverse to coupling 18 and which comprises an. insulating coupling 23- separablefrom the outermost; portion of the horizontal connecting structure and the manual operating means therefor. In'the illustrated embodiment this separability is obtained by the provision of pin and slot arrangements 24 and 25' whichenable the-coupling 23 to swing into'the position indicated in dotted lines in Fig. 2, when it is desired to disassemblethe drive mechanism-for the purposes explained below;

A manually operablexdev-ice :whichpincludes a crank. handle 26- -is mounted on a .cover: plate 27 which, as.

illustrated in, Fig. 1; serves both .tot carry' the-manual operating device and 'to coverfxan ropeningtformed in the-lower part of "transformer-"casing -1. The opening covered by cover 'plate 27 is sufiiciently large :to allow? It is in. this space removal of the gears 28-22, coupling member 23 and their associated parts, if it is necessary for the purposes of maintenance. Cover plate 27 is formed with an aperture 28 which serves as an inspection port and which is closed by a removable plate 28a.

The transformer drive mechanism of the present invention is preferably equipped with both an internal position indicator 29 and an external position indicator 30, internal indicator 29 being provided for initially aligning the connecting members in the interior of the transformer cator 29 is also preferably of the sameconstruction. As

shown in Fig. 4, indicator 30 comprises a flanged member 31 having bosses 32 on which numerals are placed corresponding to the different rotational positions of switch contact 16. A serrated ring 31a is secured to flanged member 31 centrally thereof, ring 31a being provided with numerals arranged to correspond with the numerals r on bosses 32. A mask ring 33 having a cutout 36 is superimposed on serrated ring 31a and is rotatable relative thereto so as to selectively uncover through cutout 36- the numerals on the surface of serrated ring 31a. Mask ring 33 is provided with an eccentrically arranged circular recess in which an eccentric member 34 fits, ring 33 being movably engaged by eccentric member 34 -which is secured to and rotatable within the circular recess by central shaft 35, which inturn is rotatable by handle 26.

Mask ring 33 is equipped with roller members-33a, b

projecting from the bottom thereof and adapted to fit into recesses 31b of serrated ring 31a. During turning of shaft 35 by handle 26, the consequent turning of cocentric member 34 within the circular recess imparts a swingingmovement to mask ring 33 which turns in the opposite sense to the rotational movement of shaft 35, the roller members 33a, b being alternately inserted in recesses 31b during this swinging movement. In the operation of the position indicator as described, the movements of eccentric member 34 and mask ring- 33 are similar to the movements of the crank. arm and contact members ofthe'tap changer switch described in Patent- 2,255,501 mentioned above. The cutout 36 of mask ring 33uncovers, during rotation of handle 36 and shaft 35, the indicator numeral which corresponds to the rotational position of contact 16 of tap switch 11. Due to the construction of the positionindicators 29 and 30 r as just described, the indicator mechanism undergoes movements corresponding tothose of the switch mech-- anism and thereby correctly shows at all times and in all rotational positions of handle 26 the exact position of the switch contact 16, and thereby accurately indicates the particular voltage ratio of the transformer;

Handle. 26 which is mounted on-the exterior of cover plate 27 may be of collapsible type so as to assume the position indicated in dotted lines in Fig. 2 when not in use. In this inoperative position, the handle 26 is covered by a protective cap member 37 which may be removably attached by bolts or the like to the position indicator 30. A suitable stufiing box 38 is provided for sealing the insulating oil within housing 1 at the point where the horizontal connecting structure passes'through the coverplatef structure.

It desired, a gasket 37' or other suitable sealing means"- may be placed on cap member 37 so that the latter mem ber provides a hermetic seal whenbolted in place, thus insuring against possible loss of oil through stutfing box-38.

It will be seen from the above-description and the accompanying drawings that the novel tap changer drive arrangement of the present invention affords a convenient means for operating a tap changer switch from floor level, which is especially desirable in the case of large power transformers, which often have a height of feet or more. The present arrangement in accordance with the invention also substantially avoids any risk to the operator by reason of possible contact with electrically charged parts of the transformer. Further, the present arrangement facilitates accurate checking of the position of the tap changer switch mechanism and allows easy access to the drive mechanism for maintenance and repair, if this should be necessary.

While there has been shown and described a preferred embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention, and that it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a transformer apparatus, a housing having a top, a bottom and a side wall and adapted to rest with its bottom on a supporting surface so as to extend upwardly therefrom substantially above the height of an operator on said supporting surface, said housing being formed with an opening in the lower portion of said side wall thereof; cover means removably attached to said side wall of said housing closing said opening therein, said cover means having an inspection port formed therein and a removable closure therefor; a winding arranged within said housing extending upwardly therein; switch means arranged within said housing adjacent said winding above the height of the operator and being connected to said winding, said switch means including contact means movable to different positions for varying the effective number of turns of said winding; manually operable drive means mounted on said cover means of said housing at the exterior thereof, so as to be located at the lower portion of said housing within reach of an operator on the supporting surface on which said housing rests; connecting means arranged within said housing extending downwardly from said switch means and connecting said manually operable drive means to said movable contact means of said switch means, said connecting means being turnable by said manually operable drive means for moving said contact means to different positions, and being separable to allow removal of said cover means together with said manually operable means from said housing; internal indicating means associated with said connecting means for indicating the position of said movable contact means of said switch means and arranged so as to be visible through said inspection port of said cover means from the exterior of said housing; and external indicating means associated with said manually operable drive means and visible from the exterior of said housing for indicating the position of said movable contact means of said switch means.

2. In a transformer apparatus, a housing having a top and a bottom and adapted to rest with its bottom on a supporting surface so as to extend upwardly therefrom substantially above the height of an operator on said supporting surface, said housing being formed with an opening in the lower portion thereof; cover means removably attached to said housing and closing said opening therein; a winding arranged within said housing extending upwardly therein; a core within said housing extending upwardly through said winding and along the bottom of said housing; support means within said housing having a vertical supporting portion holding said core and a horizontal supporting portion supporting said winding; switch means arranged within said housing adjacent said winding above the height of the operator and being connected to said winding, said switch means being operable for varying the effective number of turns of said winding; manually operable drive means mounted on said cover means of said housing at the exterior thereof so as to be located at the lower portion of said housing within reach of an operator on the supporting surface on which said housing rests; first elongated connecting means arranged within said housing extending directly downwardly from and connected to said switch means and journaled in said horizontal supporting portion of said support means; and second elongated connecting means extending at one end through said cover means into the interior of said housing transversely to said first elongated connecting means and being rotatably carried at its other end by said vertical supporting portion of said support means, said second elongated connecting means operatively connecting said manually operable driving means to said first elongated connecting means, so that said switch means may be operated by manipulation of said manually operable drive means by an operator on said supporting surface.

3. In a transformer apparatus, a housing having a top and a bottom and adapted to rest with its bottom upon a supporting surface so as to extend upwardly therefrom substantially above the height of an operator on said supporting surface, said housing being formed with an opening in the lower portion thereof; cover means removably attached to said housing and closing said opening therein; a winding arranged within said housing extending upwardly therein; a core within said housing extending upwardly through said winding and along the bottom of said housing; support means within said housing having a vertical supporting portion holding said core and a horizontal supporting portion supporting said winding; a tubular member arranged within said housing extending upwardly along said winding adjacent thereto and mounted at its lower end on said horizontal supporting portion of said support means; switch means mounted within said tubular memberabove the height of the operator and being connected to said winding, said switch means being operable for varying the effective number of turns of said winding; manually operable drive means mounted on said cover means of said housing at the exterior thereof so as to be located at the lower portion of said housing within reach of an operator on the supporting surface on which said housing rests; first elongated connecting means extending in said tubular member directly downwardly from and connected to said switch means and being journaled in said horizontal supporting portion of said support means; and second elongated connecting means extending at one end through said cover means into the interior of said housing transversely to said first elongated connecting means and being rotatably carried at its other end by said vertical supporting portion of said support means, said second elongated connecting means operatively connecting said manually operable driving means to said first elongated connecting means, so that said switch means may be operated by manipulation of said manually operable drive means by an operator on said supporting surface.

4. In a transformer apparatus, a housing having a top and bottom and adapted to rest upon a supporting surface so as to extend upwardly therefrom substantially above the height of an operator on said supporting surface, said housing having a wall formed with an opening in the lower portion thereof; cover means removably attached to said housing and closing said opening therein; a winding arranged within said housing extending upwardly therein; a core within said housing extending upwardly through said winding and along the bottom of said housing; support means within said housing having a vertical supporting portion holding said core and a horizontal supporting portion supporting said winding, said vertical and horizontal supporting portions, said lower wall portion and said bottom of said housing substantially defining a free space at the bottom of said housing; switch means 7 arranged within said housing adjacent said winding above the height of the operator and being connected to said winding, said switch means being operable for varying the effective number of turns of said winding; manually operable drive means mounted on said cover means of said housing at the exterior thereof so as to be located at the lower portion of said housing within reach of an operator on the supporting surface on which said housing rests; first elongated connecting means arranged within said housing connected to said switch means and extending directly downwardly therefrom into said free space; second elongated connecting means operably connected to 8 said manually operable driving means and extending through said-cover means into said free space at the bot tom of said housing; and intermediate connecting means arranged in said free space connecting said first and second connecting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,709,724 Hill V Apr. 16, 1929 1,801,125 Treanor Apr. 14, 1931 2,177,109 Hill Oct. 24, 1 939 

